In the past, it has been a simple practice to employ a variety of straps, ropes, bungee cords and the like for holding cargo or other loads in a secure position on a vehicle. At the other end of the spectrum are the ratcheted type tie-down devices often use on tractor trailers which employ ratchet teeth and spring loaded catch mechanisms. Such tensioning apparatuses serve as tensioning and tie-down devices, with lashing straps constituting the preferred embodiment of the tensioning and tie-down means. In ratcheted type tie-down devices, each tie-down strap usually has a hook at one end for securing to the trailer frame in which the other end is coupled with the ratchet tooth and spring loaded catch mechanism for adjusting the length of the strap that is disposed between the two ends.
Referring now to FIGS. 1A and 1B there is illustrated a conventional tie-down device 10. These type devices typically include a U-shaped frame having side walls with a rotatable spindle 15 or winding shaft bridging the space between the side walls and supported via thru-holes. The U-shaped frame also includes an assembly 11 for coupling to the trailer frame. Generally, these device are maintained of the trailer even during times of non-use. In some cases, these devices may be integrated with the trailer and become integral part thereof.
The spindle 15 includes a opening 17, such as a thru-slot, for securing the free end of the strap. At one end of the spindle 15 is a heavy duty flange end which supports coupling with a tightening lever (not shown). More specifically, the flange end includes a plurality of openings located circumferentially in which each can support one end of the lever such that the lever can be inserted and used as a cheater bar to tighten the strap. The other end of the spindle is coupled to a ratchet 19 having inclined teeth into which a pawl 21 (i.e., tooth catch mechanism) drops so that motion can be imparted to the spindle to allow motion in one direction only. The pawl 21 is shown in a released position and would be engaged if pivoted in a direction indicated by the dashed line. Further, ratchets used on conventional tractor trailer tie-downs, such as that shown, have a thru-hole 23 which runs parallel with the length of the spindle 15.
As a user tightens the device via the lever, the pawl 21 clicks as it catches each tooth of the ratchet 19 as the device is tightened. During the unload procedure, the pawl 21 is removed from engagement with the teeth and the take-up spindle 15 spins free under the influence of the forces from the strap allowing the strap to be released or lengthened.
Typical operation includes encircling the load to be secured with the strap, securing the strap hook to a frame portion of the trailer and pulling the free end of the lashing strap through the slot 17 within the spindle 15. Then the spindle 15 is rotated by inserting the lever and pivoting it in the tensioning direction. Typically, the lever is only pivoted a partial turn and is removed and re-inserted in another flange opening for further tensioning. The tensioning lever drives the externally-toothed ratchet wheel 19 in the tensioning direction of the spindle, so that the lashing strap is wound around the spindle which acts in the manner of a wind-up reel and is thus charged with an increasing lashing tension.
Conventionally, with no tension on the strap (i.e., when not in use), the strap is wound by the user grasping the flange end 13 and turning the spindle 15 (as this is quicker than using the lever), with each turn winding only a small portion of the strap length. The manual winding of each tie-down strap takes an individual several minutes each to wind, causing fatigue, and in some instances, contributing to carpal tunnel syndrome due to the repetitious motion associated with winding each strap.
For practical reasons which should be apparent, it is most convenient for the straps to be stored on the spindle 15 and not in some other location when the tie-downs are not in use. However, because of the difficulty, health hazards, and/or time consumed in winding the entire length of the strap onto the spindle 15, truckers remove the straps from the tie-down devices 10 and stored them in some other location (usually in the tractor) and do not wind them onto the spindles 15.
There is a need of a means to increase efficiency and decrease effort and energy in winding tie-down straps when not in use. The improvement efficiency would allow for faster cargo loading and unloading, which in turn, allows for faster and more frequent deliveries of cargo. Further, the decrease in repetitious motion associated with manual winding would reduce the fatigue created by the manual griping and turning of the wind-up reel.